Progressive saturation magnetic amplifier



April 12, 1966 M. STIMLER PROGRESSIVE SATURATION MAGNETIC AMPLIFIERFiled July 10, 1962 FlG.l.

INVENTOR. MORTON STIMLER United States Patent 3,246,234 PROGRESSIVESATURATION MAGNETIC AMRLIFIER Morton Stimler, 8308 14th Ave,Hyattsville, Md. Filed July 10, 1962, Ser. No. 208,975 5 Claims. (Cl.323-6) The invention described herein may be manufactured and used by orfor the Government of the United States of America for governmentalpurposes without the payment of any royalties thereon or therefor.

This invention relates to a constant current device and moreparticularly to a magnetic amplifier employing a tapered core forprogressive saturation to provide a constant current load circuit.

It was discovered when working with progressive saturation devices thatprogressive saturation techniques could be advantageously applied tomagnetic amplifier circuits. In the particular circuit of this inventiona tapered saturable core is saturated to a desired predetermined level.Control windings in the primary and secondary circuits are utilized toshift the saturation level of the tapered saturable core such that aconstant current is provided in the load or secondary circuit of themagnetic amplifier.

An object of this invention is to provide a magnetic amplifier having aconstant current output characteristic.

Another object of this invention is to provide a constant output currentdevice utilizing progressive saturation techniques.

A further object of this invention is to provide a magnetic amplifierutilizing progressive saturation techniques for regulating current flowin the load circuit of the magnetic amplifier.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawing wherein:

FIG. 1 illustrates a circuit of a preferred embodiment of thisinvention;

FIG. 2 of the drawing illustrates a powdered iron tapered core suitablefor use with the present invention; and

FIG. 3 is a sectional view of the powdered iron tapered core of FIG. 2.

Referring now to FIG. 1 of the drawing, in which a schematic diagram ofa preferred embodiment of this invention is illustrated, core 11represented by a progressive saturation symbol has a uniformly varyingcross sectional area. The dashed line indicates the degree of saturationwhich, for example, is approximately one-half of the length of the coreshown in FIG. 1. Core 11 is supplied with primary winding 13, controlwindings 15 and 17 and secondary winding 19. Primary winding 13 isconnected to an A.C. voltage source 21. Control winding 15 is connectedto a feedback network 23 of the primary circuit. Control winding 17 isconnected to the feedback network 25 at the secondary circuit. Thewindings 15 and 17 are connected in opposition to the winding 13. A loadresistor 27 is connected to secondary winding 19 through a portion offeedback network 25.

In operation, under normal conditions, a desired magnitude of currentwill flow through load resistor 27 as determined by the parameters ofthe circuit. That is, when core 11 is saturated to a certain level, forexample, 50% of the length of the core, an input voltage of a givenmagnitude applied from A.C. source 21 to primary winding 13 will producea current flow of a certain magnitude in secondary winding 19 and loadresistor 27.

Under these conditions the feedback networks will cause control currentsto flow in the control windings and a condition of equilibrium willexist with the core 11 having 50 percent of its length saturated. It isto be noted that (negligible) voltage will be induced in the turns ofsecondary winding 19 on the saturated portion of the core. That is, onehalf of the turns of secondary winding 19 will be inactive when core issaturated for 50 percent of its length as indicated in the aboveconditions.

If a change in the magnitude of the voltage of source 21 should occur,for example if the voltage should increase, increase in voltage willtend to cause an increase in the current flow through primary winding 13as a result of an increase in voltage across primary winding 13. At thesame time there will be an increase in current flow through controlwinding 15 which will cause an increase in the saturation level of core11. As core 11 becomes saturated over a greater portion of its lengthdue to this increase in control current in winding 15, an additionalnumber of turns of secondary winding 19 in the newly saturated portionof core 11 will become ineffective, reducing the number of effectiveturns of winding 19, reducing in turn the voltage developed acrosssecondary winding 19 and hence reducing the current flow through load 27offsetting the tendency for an increased load current by the increase involtage across the terminals of primary winding 13. Thus the currentfiow through load resistor 27 is kept at a constant value. If the loadcurrent actually increased in value, the increased current flow inwinding 17 would further saturate core 11, inactivating more of theturns of secondary winding 19 to reduce the current flow through loadresistor 17 to the desired design level.

If, on the other hand, the voltage of source 21 should decrease, thetendency for the current through secondary winding 19 and load resistor27 to decrease will be off- 7 set by the reduction in current fiowthrough control winding 15 which will decrease the saturation level ofcore 11 and increase the number of active turns in secondary winding 19.If there should be a decrease in the current fiow through load resistor27, this reduction in current flow will reduce the current flow incontrol winding 17 further reducing the saturation level of core 11 andfurther increasing the number of active turns in secondary winding 19,causing an increase in the voltage drop across winding 19 and anincrease current flow through load resistor 27.

Referring now to FIGS. 2 and 3 of the drawing, a tapered core 51 may beutilized in the circuit alternatively into core 11. This core may bemade of powdered iron, ferrite or suitable laminated ferromagneticmaterials. Square hysteresis loop materials may be employed, if desired.

Whereas feedback networks 23 and 25 are shown in block diagram, as iswell known in the art, these networks may be, for example, transformercouplings. Rectifiers may be included in the bias or feedback circuitsto provide a DC. current for bias windings 15 and 17.

Obviously many modifications and variations are possible in the light ofthe above teachings. It is therefore to be understood, that within thescope of the appended claims, the invention may be practiced otherwisethan as specifically described.

What is claimed is:

1. A magnetic amplifier comprising a saturable tapered core, a primarycircuit, a secondary circuit, said primary circuit including a primarywinding on said core and a first control winding on said core, saidsecondary circuit including a secondary winding on said core, a secondcontrol winding on said core, and a load means, means adapted to connectsaid primary winding and said first control winding to an A.C. voltagesource whereby said amplifier may be energized, means connecting saidsecondary winding to said load means, said second control winding beingconnected to said means connecting said secondary winding to said loadmeans, said secondary winding having turns evenly disposed along thelength of said core whereby an increase in saturation level of said coredecreases the number of effective turns of said secondary winding and adecrease in saturation level of said core increases the number ofefiective turns of said secondary winding to decrease or increase therelative voltage induced across said secondary winding respectively,said first and second control windings operative to increase thesaturation level of said core when the voltage of said source increasesto reduce the efifective turns in said secondary to ofiset said voltageincrease, said first and second control windings operative to decreasethe saturation level of said core when the voltage of said sourcedecreases to increase the effective turns in said secondary winding tooffset said voltage decrease whereby the current in said secondarycircuit is maintained at a constant value.

2. A magnetic amplifier having a constant load current comprising asatura-ble core, a primary circuit including a primary windingconnectable to an A.C. voltage source, a secondary circuit, said corehaving a tapered configuration along the full length thereof such thatsaid core may be saturated to any desired portion of the full length ofsaid core. a first bias circuit including a first bias winding and firstunidirectional impedance means connecting said first bias winding tosaid primary circuit whereby a change in voltage of the source willcause a directly proportional change in the saturation level of saidcore, said secondary circuit including a secondary winding on said core,a load means connected to said secondary winding, a second bias circuitincluding a second bias winding on said core and second unidirectionalimpedance means connecting said second bias winding to said secondarycircuit whereby a change in the voltage across said secondary windingwill cause a directly proportional change in the saturation level ofsaid core, said secondary winding having turns evenly distributed alongthe full lentgh of said core whereby a change in saturation level ofsaid core will cause an inversely proportional change in the effectivenumber of turns of said secondary winding whereby the current in saidload means is maintained at a constant value.

3. A constant output current circuit in a magnetic amplifier comprisinga saturable magnetic core, said core having the shape of a truncatedcone where-by said core may be progressively saturated to a desiredportion of the length thereof, a primary circuit including a primarywinding on said core, and means adapted to connect said primary windingto an A.C. voltage source, a secondary circuit including a secondarywinding on said core and a load means connected to said secondarywinding, a bias circuit including a bias winding on said core,unidirectional impedance means adapted to connect said bias winding tothe A.C. voltage source whereby said core will be saturated to a leveldirectly proportional to the magnitude of the voltage applied thereto bythe A.C. voltage source, said secondary winding having turns distributeduniformly along the length of said core whereby the number of effectiveturns in said secondary winding will be inversely proportional to thesaturation level of said core and the current in said load means ismaintained at a constant level.

4. A constant load current device comprising, a saturable tapered core,an A.C. energizing circuit coupled to said core, a bias circuitincluding a bias winding on said core, a load circuit including a loadwinding on said core and load means connected to said load winding, saidload winding having turns distributed uniformly along the length of saidcore whereby a change in the saturation level of said core will cause aninversely proportional change in the efiective number turns of saidsecondary winding, said bias circuit including unidirectional impedancemeans connecting said bias winding to said energizing circuit whereby achange in voltage in said energizing circuit will cause a directlyproportional change in the saturation level of said core.

5. A constant output current device comprising, a saturable taperedcore, an A.C. energizing circuit coupled to said core, a first biascircuit including a first bias wind! ing on said co-re, an outputcircuit including an output winding on said core and an output loadmeans connected to said output winding, said output winding having turnsdistributed uniformly along the length of said core where-v by a changein the saturation level of said core will cause an inverselyproportional change in the effective number of turns of said outputwinding, said first bias circuit including first unidirectionalimpedance means connecting said bias winding to said energizing circuitwhereby a change in voltage in said energizing circuit will cause adirectly proportional change in the saturation level of said core, asecond bias winding on said core, a second unidirectional impedancemeans connecting said second bias winding to said output circuit wherebya change in voltage across said output winding will cause a directlyproportional change in the saturation level of said core.

References Cited by the Examiner UNITED STATES PATENTS Goldner et al.340--174 Silverman 307-88 De Witz 336- X-Q

4. A CONSTANT LEAD CURRENT DEVICE COMPRISING, A SATURABLE TAPERED CORE,AN A.C. ENERGIZING CIRCUIT COUPLED TO SAID CORE, A BIAS CIRCUITINCLUDING A BIAS WINDING ON SAID CORE, A LOAD CIRCUIT INCLUDING A LOADWINDING ON SAID CORE AND LOAD MEANS CONNECTTED TO SAID LOAD WINDING,SAID LOAD WINDING HAVING TURNS DISTRIBUTED UNIFORMLY ALONG THE LENGTH OFSAID CORE WEHEREBY A CHANGE IN THE SATURATION LEVEL OF SAID CORE WILLCAUSE AN INVERSELY PROKPORTIONAL CHANGE IN THE EFFECTIVE NUMBER TURNS OFSAID SECONDARY WINDING, SAID BIAS CIRCUIT INCLUDING UNIDIRECTIONALIMPEDANCE MEANS CONNECTING SAID BIAS WINDING TO SAID ENERGIZING CIRCUITWHEREBY A CHANGE IN VOLTAGE IN SAID ENERGIZING CIRCUIT WILL CAUSE ADIRECTLY PROPORTIONAL CHANGE IN THE SATURATION LEVEL OF SAID CORE.